26 The Colorado Experiment* Station. 
tities of nitric acid or nitrates as are usually understood when 
nitrates in the soil are spoken of, but of the occurrence of such 
unusual quantities as to be fatal or injurious to vegetation. I 
shall endeavor to deal with the general condition, of which only 
extreme cases are presented in this bulletin, in a subsequent one. 
The analyses of the adjacent, almost circumjacent soils, the 
alkalis and the ground waters have been given to show that they 
have nothing to do with the conditions in this orchard soil, and 
especially nothing to do with the nitrates. Apropos to the influence 
of the drainage and the character of the soil upon this question, 
we have chosen one sample of dark brown surface soil from this 
orchard collected within fifty feet of the edge of the river bank, 
and a second one, also a dark brown surface soil from another 
piece of land of which no other mention is made. Both of these 
pieces of land are naturally well drained but in addition to this 
there are four tile drains in the second piece which contains only 
thirteen acres. One of these drains was carrying about two 
inches of water while the other two that I saw were not running 
at all. There is still another drain on the land adjoining this 
on the east, which was carrying a large flow of water. The 
owner of the land stated that all of the drains carry water after 
he irrigates the land, showing conclusively that the land drains 
freely. The soil is sandy, very similar to that of Case 8, with 
which we have joined it. I was informed that some of the drains 
have been laid four years. Laboratory No. 1067 is a sample from 
Case 8, collected March 27, 1911, fifty feet from the river bank. 
We give two analyses of this sample, one of the water-soluble 
portion, the other a mechanical analysis of the soil. The water- 
soluble in this sample equaled 8.165 percent of the air-dried soil. 
Laboratory No. 1076 is a similar sample collected from the drained 
land and also within fifty feet of the river bank and not less than 
twelve feet above the river bed. These soils are so similar that the 
mechanical analysis of the one faithfully represents the other. 
The water-soluble in No. 1076 equalled 9.882 percent of the air- 
dried sample. 
ANALYSES 
XXIX 
XXX 
Water-Soluble 
Water-Soluble 
Laboratory 
Laboratory 
No. 1067 
No. 1076 
March 27, 1911 
May 2, 1911 
Percent 
Percent 
Calcic sulfate . 
. 21.826 
19.494 
Calcic chlorid . 
. 23.971 
1.647 
Magnesic chlorid . 
. 20.534 
16.435 
Potassic chlorid . 
. 2.880 
1.716 
Sodic chlorid . 
. 26.846 
57.106 
Sodic nitrate . 
. 3.807 
3.374 
Iron and Aluminic oxid. 
0.101 
Silicic acid . 
. 0.138 
0.127 
100.000 
100.000 
